On any given evening nowadays, veteran Twin Cities singer Mick Sterling might be growling Joe Cocker songs, or crooning some Bing Crosby. Tonight, though, he's harmonizing like the Bee Gees.

It's not clear which Bee Gee he is, but it's definitely not Barry Gibb. The high, fluttering voice at this two-hour tribute show is being handled by Cate Fierro, who is trying to get a full house at Chanhassen Dinner Theatres moving to "Stayin' Alive."

She demonstrates John Travolta's hand movements from the movie "Saturday Night Fever" to the AARP-age crowd. Jimmy Delia, a transplanted New Yorker, is one of the few people who knows he should be dancing.

"A lot of Minnesotans don't get up and dance in the aisles; they just sit," Delia said the next day in his unmistakable Brooklyn accent. "Me and this girl I took on a first date, she and I were rocking."

Whether on their feet or in their seats, baby boomers are boogieing to heyday hits at nightspots across the Twin Cities area.

Don't think Elvis impersonators or heavy-metal dudes in wigs and Spandex. This new wave of tribute shows is a classy celebration of classic songs, whether it's the Eagles, Barbra Streisand, Frank Sinatra or a night devoted to one-hit wonders.

These aren't dive bars or pickup joints, either. Fans are paying $40 a seat and filling posh sit-down venues, such as Chanhassen's 236-seat Fireside room, the Dakota in downtown Minneapolis and Crooners supper club in Fridley.

Many local bar stars from the 1980s and '90s have abandoned original music in favor of the sounds that inspired them. Sterling alone has assembled more than 20 tribute shows — from Elton John to Andy Williams and Bing Crosby to the Monkees.

The Fabulous Armadillos, whose members have played with the likes of Jonny Lang and GB Leighton, sell out their annual season of shows at St. Cloud's 188-seat Pioneer Place theater before they even announce what they'll play.

Mary Jane Alm, a Minnesota barroom mainstay since the late '70s who's now on the tribute circuit, performed more shows in December — 23, to be exact — than any month in her entire career.

"I feel like this has breathed new life into the live music scene in this town," said Alm, who participates in eight tribute revues and still gigs occasionally with her own band.